The present invention relates to digital television, and more particularly to a method and apparatus by which MPEG-2 programs or the like may be extracted from a transport stream and delivered via the same or another transport stream at a fraction of the program""s original transport rate, or stored using less capacity than required to store the original transport stream. In this manner, the invention enables a receiving device to receive, store, and decode the program at some future, user-initiated time.
In bandwidth-limited systems, a tradeoff exists between the number of digital TV programs that may be delivered concurrently and their subjective quality. A need may also exist to allow the delivery of programs in non-real-time as enhanced services which do not impact the quality of programs delivered in real-time. Such enhanced services could include commercial advertisements that are applicable to the receiving device and xe2x80x9cplayed outxe2x80x9d by remote control (e.g., during a commercial break). Moreover, it would be advantageous to provide a capability to deliver programs requested by the user of the receiving device on a non-real-time basis, i.e., after the original real-time transmission of a program.
In the past, the issue of picture quality versus the number of programs to be carried over a given bandwidth has been addressed by employing statistical multiplexing (see, e.g., U.S. Pat. No. 5,216,503 to Paik et al.). Services such as video-on-demand have also been provided where the bandwidth necessary to convey such information is accommodated by additional physical channels.
Various schemes for selecting between different real-time television signals are also known in the prior art. For example, U.S. Pat. Nos. 5,155,591 and 5,231,494 describe targeted advertising that is delivered in real-time. Such advertising may be selected by a decoder employing customer xe2x80x9cprofilesxe2x80x9d, as disclosed in U.S. Pat. No. 5,758,257. However, such schemes are predicated on the transmission of concurrent real-time (analog and digital) TV programs.
U.S. Pat. No. 5,619,337 describes a system for recording MPEG-2 transport streams. The goal is to address the recording of a single program stream extracted from a multi-program transport stream onto a device such as a digital VCR for subsequent playback.
It would be advantageous to provide a bandwidth-efficient system for conveying digital television programs and/or other content (e.g., multimedia) in their original format, which may comprise, for example, MPEG-2 transport packets. The system should allow the programs and other content to be provided on a non-real-time basis for later use by a recipient. Such content should be able to be easily received, recorded on a digital VCR or otherwise stored, and played back at the user""s convenience. It would be still further advantageous to permit the communication of multiple digital TV programs and/or other content with little or no impact on the quality of real-time programs delivered via the same transport stream.
The system should enable the delivery of pre-encrypted content to one or more decoders in non-real-time, wherein authorization data is provided to the decoders at a common time to enable decryption and playback.
The present invention provides a method and apparatus enjoying the aforementioned and other advantages.
The present invention makes use of allocated bandwidth and/or bandwidth made available by variable bit rate (VBR) program streams to provide a bandwidth-efficient scheme for conveying content such as digital television programs and/or multimedia information in their original form (e.g., MPEG-2 transport packets). A large portion of currently available MPEG-2 decoder hardware and/or software may be used to decode content delivered per the invention. The invention also, in effect, allows the delivery of multiple non-real-time digital TV programs and other content with little to no impact to the quality of content delivered in real-time via the same transport stream.
A particular method in accordance with the invention provides data of at least a first program of a first data stream in an input transport stream, where the transport stream includes data of at least a second data stream. The method includes the steps of: extracting null packets and/or nonessential packets of the first data stream, providing an annotation packet that provides information regarding the extracted packets, and inserting the annotation packet and program packets of the first program into the input transport stream in place of null packets of the second data stream to form an output transport stream.
A decoding method is provided for processing an output transport stream that includes data of at least a first program and a second data stream. The method includes the steps of: recovering program packets of the first program, storing the recovered packets at a storage device, recovering an annotation packet from the output transport stream, and regenerating a number of null packets of the first program based on the recovered annotation packet to provide regenerated data that is suitable for decoding. The output transport stream is formed at an encoder by extracting null packets and/or nonessential packets of a first data stream that carries the first program, and inserting the annotation packet and the program packets of the first program into an input transport stream in place of null packets of the second data stream. The annotation packet provides information regarding the extracted packets.
Corresponding apparatuses are also presented.